Inorganic fiber riser sleeves



y 22, 1969 H. E. KQNRAD ETAL 3,456,914

INORGANIC FIBER RISER SLEEVES Filed Oct. 25. 1965 INVENTORS. H QWAKD EKat/RAD BY SIDNEy SPE gad j y United States Patent 3,456,914 INORGANICFIBER RISER SLEEVES Howard Edwin Konrad and Sidney Speil, Somerville,N.J., assignors to Johns-Manville Corporation, New York, N.Y., acorporation of New York Filed Oct. 23, 1965, Ser. No. 504,231 Int. Cl.B22d 7/10; C04b 35/68 US. Cl. 249201 14 Claims ABSTRACT OF THEDISCLOSURE Resilient and durable, self-supporting riser sleeve productsfor metal casting composed primarily of refractory fiber and binder.

This invention relates to riser sleeves for metal casting, and inparticular to improved riser sleeves of a novel and advantageouscomposition and construction.

Riser sleeves, which provide reservoir chambers for molten metal to feedthe same back into the mold cavity to compensate for shrinkage duringsolidification of the cast metal Within the mold, have conventionallybeen constructed of gypsum plaster or of common exothermic materials.Such materials, however, normally provide constructions which lackresilience and durability, are brittle and thus particularly susceptibleto breakage through handling and use. Moreover, the gypsum sleeves arefrequently wanting in service, and the exothermic materials employed inthe latter type are costly.

It is the primary object of this invention to provide a riser sleeve orconstruction therefor alfording a low cost product of improved thermalinsulating properties and which is highly resilient and resistant tobreakage and will effectively endure the high temperatures andaggressive effects of common molten metals and alloys.

It is also a principal object of this invention to provide a risersleeve which is economical to manufacture and may be formed in any of awide variety of sizes, dimensions and configurations, is versatile inuse in that it can be easily out without special tools or care to alterits configuration or reduce its dimensions and presents a rough exteriorsurface which efiects better keying or union with the sand mold.

It is a further object of this invention to provide riser sleeves whichare compatible with and resist most molten metals and alloys and thetemperatures of their melts and which are not wetted or attacked bycommon molten metals.

It is a still further object of this invention to provide an economicalriser sleeve which may be roughly handled under abusive factoryconditions without damage or breakage.

These and other objects and advantages of this invention will becomemore apparent from hereinafter detailed description thereof.

The drawing comprises a pictorial view illustrating a typicalcylindrical riser sleeve construction and product formed of the fibrouscomposition of this invention.

This invention consists of the construction or formation of improvedriser sleeves from compositions comprising primarily inorganic fibersand binder, preferably inorganic binder, and the resultant products ofsuch compositions which are self-supporting and of highly effectivephysical and thermal properties providing a practical, handleable andversatile product for use with typical molten metals and castingtechniques and molds therefor. Specifically, the riser sleeves of thisinvention constitute bodies or units comprising essentially andpredominantly an intimate admixture of apt inorganic fibers andinorganic binders Patented July 22, 1969 which may be formed byconventional means and in sub stantially any common or typicalconfiguration appropriate for molten metal risers.

Suitable inorganic fibers for the practice of this invention comprisecommon manufactured fibers, or synthetically formed as opposed tonatural mineral fibers such as asbestos, possessing effective resistanceand integrity at temperatures of at least about 1000 F., or morespecifically an effective temperature resistance generally in excess ofthat of the particular molten metal material to be handled. Numerous aptfiber compositions or products together with their effective temperatureresistance and other physicals are known in the art and literature, andare available in the market; for example, Product En ineering, Aug. 3,1964, pages 96 through 100 and Aug. 31, 1964, pages 63 through 66. Theytypically comprise fibers formed from melts of compositions generallypredominantly of silicates of calcium, aluminum and the like diortri-valent metals, and include the familiar rock wools, mineral or slagwools, glass wools or fibers of high temperature melting conditions,ceramic fibers, and in particular the highly refractive fibersconsisting wholly of alumina and silica or primarily of alumina andsilica with added oxides such as titania or zirconia, or borosilicatefibers, or essentially pure silica fibers, etc., and assorted aptmixtures of any of the foregoing.

Inorganic binders preferably constitute clays, for example, bentonite orhectorite due to their case of application, I

effective integrating capacity and low cost, among other useful andbeneficial properties thereof. However, other inorganic binders mayserve either alone or in combination with clay or other given materials;for example, common temperature resistant binders comprise common alkalimetal silicate binders of sodium or potassium silicate, borax,phosphoric acid and assorted phosphates or salts as for example aluminumphosphates, colloidal mica, colloidal silica, colloidal alumina such asboehmite, etc.

Also, organic binders such as resins, starch, glues, dextrin,polysaccharide gums, drying oils, rubber, asphalt, which are generallytemporary or fugitive in nature in that they decompose and are destroyedat the elevated temperatures of molten metals, are neverthelesseffective in uniting the fibrous body and particularly useful inintroducing Wet or green Strength into the products. And in combinationwith high proportions of inorganic fiber, organic binders such as starchalone will provide bodies which will retain their integrity even when indirect contact with many molten :metals during its solidification.

Aside from the essential and predominant high temperature resistantinorganic fibers and binder components referred to above, thecompositions of this invention for the formation of riser sleeves mayembody ancillary ingredients to, for example, facilitate manufacturingor formation of the sleeves, introduce or modify various properties suchas the degree of porosity, bulk or density, and which are compatiblewith the particular molten metal materials with which the sleeve will beused, and in amounts not suflicient to change the basic and essentialcharacteristics and/or functions of the primary components of theproduct. For instance, when the riser sleeves are formed by filtermolding and ingredients from a dilute aqueous slurry, the most expedientand thus preferred means of manufacturing fibrous riser sleeves orcontainers of typical configurations, it is desirable to include smallquantities of an organic or cellulosic fiber, such as kraft pulp, tofacilitate the filter molding and increase the porosity of the productwhich facilitates removal and dissipation of any vapors formed duringpouring of the molten metal and thereby retarding boiling andsplattering of the melt. Moreover the products of this invention cannormally tolerate minor amounts, for example up to about 50% by weight,of fillers which do not materially affect the properties or function ofthe essential and viable components or of the product, either for costreducing or other purposes. For example likely fillers comprise salvageor scrap from either unused or used riser sleeves of this invention,assorted refractory grogs and particles, light weight filler such asexpanded perlite, calcined diatomaceous earth, or kyanite, calcinedkaolin, alumina, silica, pyrophyllite, etc.

Effective and readily produced riser sleeves of this invention compriseproducts or constructions composed of inorganic high temperatureresistant fibers and binders, either with or without ancillarycomponents, generally within the relative proportions, in approximatepercentages by weight of: inorganic fibers40 to 95%; binder-5 to 40%,which preferably comprises 3 to 20% of inorganic binder and up to 20% oforganic binder; organic fiber-O to 20%; and filler to 50%. Riser sleeveproducts of generally overall optimum properties are provided by thepreferred ranges of essential and ancillary ingredients, in approximatepercentages by weight, of: inorganic fiber45 to 90%; inorganic bindersuch as bentonite clay-4 to 15%; organic binder such as starch- 3 to10%; organic fiber such as cellulosic pnlp4 to 15%; and filler-0 to 35%.

The fibrous riser sleeves, or molten metal retainers of this inventioncan be formed and produced from the above given compositions by means ofconventional techniques for shaping and integrating an admixture offiber and binder into a shape retaining configuration including commonmeans of casting or molding, felting, etc. Preferred techniquescontributing to product uniformity and consistency consist ofintegrating and consolidating a body of the designed shape from adispersion of the ingredients in an aqueous or the like suspendingmedium by filter molding. The typical riser sleeve configurations, amongothers, can be expediently formed by vacuum filter molding withperforated or screened male or female molds defining the configurationand filtering from a dilute water slurry of the fiber and binder, etc.,whereby the product may be uniformly shaped and formed by accretion ofthe constituent solids from the liquid medium passing through the filtermold and thus extended to the required dimensions whereupon theformation is terminated by removal from the aqueous medium and theresulting formed body partially dried by maintaining the vacuum. Thistechnique, in conjunction with the fiber based formulations of thisinvention, provides bodies which can be promptly removed from the moldswhile wet and immediately thereafter are handleable and resist breakagethrough dropping and the like typical abusive factory methods. Otherforming means can of course be applied such as simple pan casting orpress molding more concentrated slnrries of the ingredients to impartform and remove the liquid medium. However, procedures wherein formationof the product is through gradual and relatively uniform accretion ofthe components as in filter molding either with or without a vacuum orother actuating means, are preferred as the components are moreuniformly united and consolidated into a continuous integrated massforming the ultimate body.

Referring to the drawing, although the transverse configuration of ariser sleeve product shown as 10 may be of any design, it is usuallymore expedient both as to their manufacture and use that they be ofgenerally round or cylindrical configuration as illustrated. Thepreferred riser sleeve products of the fibrous construction of thisinvention, as shown in the drawing, constitute a cylindrical tube-likebody 12 formed of an annular wall 16 provided with an internal cavity 14passing therethrough. Due to the basically fibrous composition of theannular wall 16 forming the cylindrical tube body 12, the overallstructure is highly resilient but of more than ample strength to supportitself and contain molten metal within the reservoir chamber formed bythe internal cavity 14.

The following examples comprise illustrations of the preferred andtypical compositions and formation techniques for the manufacture of theproducts for this invention and the properties thereof demonstrating thepronounced improvements and advantages of this invention. It is to beunderstood that the specific proportions or ratios and components of thecompositions given in the examples as well as the means, conditions,techniques, etc., set forth therein are primarily exemplary and are notto be construed as limiting this invention to any specific ingredientsor proportions thereof and compositions other than those hereinbeforespecified as essential.

A number of riser sleeves in a standard product configuration anddimensions of cylindrical sleeves measuring 12 inches in length and ofvarious internal diameters of from 1 to 12 inches in /2-inch incrementsand standard wall thicknesses of about to /2 inch, were vacuum filtermolded on the outside of cylindrical screen core molds provided withinternal vacuum, from a dilute aqueous slurry having a solids content ofabout 0.84% by weight of each of the inorganic fiber and binder, etc.,compositions given in the hereinafter examples. Molding was effected bysubmerging the filter cores into the suspension of ingredients andliquid medium with an internally applied vacuum for a period of about 8to 16 seconds depending upon the sleeve diameter, then withdrawing themold and accreted solids forming the sleeve and retaining the vacuumfollowing removal of the sleeve from the slurry for about 10 to 20seconds, again depending upon the sleeve diameter, to partially dry theproduct whereupon it may be removed from the mold core. Such productsexhibit average dry densities of about 10 to 12 pet. The solidconstituents of each dilute aqueous slurry and approximate compositionof the formed products were:

The refractory fiber of Examples 1 and 4 consisted essentially ofapproximately equal parts of alumina and silica, providing an effectivetemperature resistance in the order of 2300" F. and constitutedJohns-Manville Corporations product Cerafelt. The high iron mineral woolfiber of Example 2 was an Eagle Picher Corporation product identified ashigh iron mineral wool I-ID-2 produced from a lead slag high in .ironand providing an effective temperature resistance of about 1500" F. to1700 F. The mineral wool of Example 3 was a product formed frommetallurgical slags, commercially available from Johns-ManvilleCorporation as a domestic insulating material under the trademark ofSpintone and having a temperature limit of about 1000 F. to 1200 F. Ineach case the temperature endurance of the riser sleeve products wassubstantially commensurate with the temperature resistance of theinorganic fiber constituents which constitutes a property available fromthe vendor or otherwise readily determined and which is generallyprovided in the art and literature. Thus the inorganic fibrousconstituents can be readily selected on the basis of the designedapplication of the ultimate product.

Riser sleeves produced from each of the compositions of the gvenexamples were evaluated by filling the same with molten metal. The testsleeves were mounted with their base imbedded in sand and the upper partunsupported and the'metal poured into their interior, permitted tosolidify and the casted body resulting therefrom removed whereupon thesleeves were examined and found to be intact. Samples of allcompositions of the examples were tested with molten aluminum poured at15 F. and molten brass poured at 2200" F. The refractory fibercontaining products of Examples 1 and 4 performed excellently with boththe aluminum and brass whereas the mineral fiber containing compositionsof Examples 2 and 3 were very good with alumina but marginal with themolten brass which substantially exceeded their anticipated temperaturetolerances. In all cases the molten metals poured quietly with noevidence of boiling or mushrooming and there was no evidence of metalpenetration or wetting or chemical attack upon the product. Moreover, itwas evident that with careful handling the sleeves could be reused,particularly with aluminum, and provided their evident temperaturelimits had not been exceeded. The high temperature refractory fibercomposition of Examples 1 and 4 in particular appeared unaffected byeither the aluminum at 1500 F. or the brass at 2200 F. and it is evidentthat this version would be reuseable notwithstanding its exposure totemperatures approaching its apparent tolerances.

Further examples of diverse and apt fiber based compositions of thisinvention suitable for service as riser sleeves for many molten metalcasting operations comprise the following given in approximatepercentages by weight of the solids, In each of the hereinafter Examples5 through 7, the refractory fiber is composed of about equal parts byweight of alumina and silica and corresponds to that of Examples 1 and4.

EXAMPLE 5 Percent Refractory fiber 90 Starch binder EXAMPLE 6 Refractoryfiber 95 Acrylic resin 5 EXAMPLE 7 Refractory fiber 70 Bentonite clay l3Colloidal silica solids 17 (DuPonts Ludox 30% solids) It will beunderstood that the foregoing details are given for purposes ofillustration and not restriction, and that variations Within the spiritof this invention are to be included within the scope of the appendedclaims.

What we claim is:

1. An improved riser sleeve reservoir retaining chamber for molten metalcasting having a self-supporting resilient and thermally durable andinsulating hollow body forming the molten metal retaining chamberconsisting essentially of inorganic fiber consisting of at least onemetal silicate selected from the group consisting of divalent metalsilicates and trivalent metal silicates and binder.

2. The improved riser sleeve reservoir retaining chamber for moltenmetal casting of claim 1, wherein the inorganic fiber consists of atleast one metal silicate selected from the group consisting of divalentmetal silicates and trivalent metal silicates and the binder comprisesclay.

3. An improved riser sleeve reservoir retaining chamber for molten metalcasting having a self-supporting resilient and thermally durable hollowbody forming the reservoir chamber for the retention of molten metalcomprising inorganic fiber and a binder, the said body forming thereservoir chamber for the retention of molten metal being formed of acomposition consisting essentially of, in approximate percentages byweight:

Percent Inorganic fiber 45-95 Binder 540 Organic fiber 0-20 Filler 0-354. An improved riser sleeve reservoir retaining chamber for molten metalcasting having a self-supporting resi-ient and thermally durable hollowbody forming the reservoir chamber for the retention of molten metalcomprising inorganic fiber and inorganic binder, the said body formingthe reservoir chamber for the retention of molten metal being formed ofa composition consisting essentially of in approximate percentages byweight:

Percent Inorganic fiber 45-90 Inorganic binder 4-15 Organic fiber 4l5Organic binder 3-10 Filler 0-35 5. An improved riser sleeve reservoirretaining chamber for molten metal casting having a self-supportingresilient and thermally durable hollow body forming the reservoirchamber for the retention of molten metal comprising inorganic fiber andan inorganic binder, the said body forming the reservoir chamber for theretention of molten metal being formed of a composition consistingessentially of, in approximate percentages by weight:

Percent Inorganic fiber 45-95 Clay binder 3-20 Cellulosic fiber 0-20Starch binder 020 Filler 0-35 Percent Inorganic fiber 45-90 Clay binder4-15 Cellulosic fiber 0-15 Starch binder 3-10 Filler 0-35 7. Theimproved riser sleeve for molten metal casting of claim 6, wherein theinorganic fiber comprises a high temperature resistant refractory fibercomposed predominately of alumina and silica.

8. An improved riser sleeve reservoir retaining chamber for molten metalcasting having a self-supporting resilient and thermall durable hollowcylindrical body forming a reservoir chamber for the retention of moltenmetal comprising an annular wall consisting essentially of inorganicfiber consisting of at least one metal silicate selected from the groupconsisting of divalent metal silicates and trivalent metal silicates andan inorganic binder, the said annular wall being of a compositoncomsisting essentially, in approximate percentages by weight, of:

Percent Inorganic fiber 45-95 Inorganic binder -20 Organic fiber 0-20Organic binder 0-2O Filler 0-35 9. An improved riser sleeve reservoirretaining cham- 12. The improved riser sleeve reservoir retainingchamber for molten metal casting of claim 1, wherein the inorganic fiberis predominately of refractory alumina and silica composition and ispresent in amount of approximately 45 to-approximately 90% by weight ofthe riser sleeve and the binder comprises clay.

13. An improved riser sleeve reservoir retaining chamber for moltenmetal casting having a self-supporting resilient thermally durable,hollow cylindrical body forming the reservoir chamber for the retentionof molten metal comprising an annular wall consisting essentially of, inapproximate percentages by weight, 45 to 95% of refractory inorganicfiber predominately of alumina and silica, 4 to of bentonite clay, and 3to 10% of starch binder.

14. An improved riser sleeve reservoir retaining chamber for moltenmetal casting having a self-supporting resilient thermally durable,hollow cylindrical body forming the reservoir chamber for the retentionof molten Percent Inorganic fiber 45-90 Clay binder 4-15 Cellulosicfiber 0-15 Starch binder .3-10 Filler 0-35 10. An improved riser sleevefor molten metal casting 1 having a self-supporting resilient thermallydurable hollow body forming the reservoir chamber comprising an annularwallconsisting essentially of inorganic fiber and an inorganic binder,the said annular wall forming the reservoir chamber being of acomposition consisting essentially, in approximate percentages byweight, of: 80 to 90% of inorganic refractory fiber predominantly ofalumina and silica, 4 to 10% of bentonite clay, 4 to 8% of kraftcellulosic fiber 3 to 7% of starch.

11. An improved riser sleeve for molten metal casting having aself-supporting resilient thermally durable hollow body forming thereservoir chamber comprising an annular wall consisting essentially ofinorganic fiber and an inorganic binder, the said annular wall formingthe reservoir chamber being of a composition consisting essentially, inapproximate percentages by weight of: 45% of inorganic refractory fiber,4% of bentonite clay, 10%

kraft cellulosic fiber, 6% starch and 35% kyanite.

metal comprising an annular wall consisting essentially of, inapproximate percentages by weight, 45 to of refractory inorganic fiberpredominately of alumina and silica composition, 4 to 15 of inorganicbinder of bentonite clay and colloid silica solids, 3 to 10% of starchbinder, 4 to 15% of cellulosic fiber, and kyanite filler in amounts upto 35%.

References Cited UNITED STATES PATENTS 1,989,096 1/1935 Jones 106-38.92,366,485 1/1945 Brink et al. 106--38.9 3,173,451 3/1965 Slayter106-3827 3,072,981 1/1963 Davidson 249201 X 3,262,165 7/1966 Ingham249197 X 3,321,171 5/1967 Gorka et al. 249201 FOREIGN PATENTS 843,098 8/1960 Great Britain, 708,524 4/ 1965 Canada.

J. SPENCER OVERHOLSER, Primary Examiner EUGENE MAR, Assistant ExaminerUs. Cl.'X.R. 1os 3s.27, 38.5

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3456 914 Dated July 22 2 1969 Inventor(s) Howard Edwin Konrad and SidneySpeil It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 3, line 53, "Simple" should read -simp1y--, Column l, line 71,"gven" should read -given-, Column 6, line 11, "resi-ient" should readresi1ient--, Column 7, line 4, "Inorganic binder 0-20" should read-Inorganic binder 320-,

line 22, "starch binder" should read --starch Column 7,

SIGNED KND SEALED APR 2 81970 {SEAL} Anest:

Edward M. Fletcher, In. R

WIZHLIAM E SGHUYLER, Aucsung Officer Commissioner of Patents

